1. Field of Invention
The present invention relates to the field of communications network, and in particular to a method for handing disconnection between a media gateway and a media gateway controller in an NGN network.
2. Description of Prior Art
An NGN network provides various kinds of services, such as voice communications, multimedia communications and mobility, by using the SoftSwitch technology which separates control, bearer and service from each other. From the point of view of functionality, a SoftSwitch network may be divided into a service layer, a control layer, a transport layer and an access layer, from the top down. The main functional entity within the control layer is a Media Gateway Controller (MGC), which primarily provides functions such as call control, connection control and protocol handling etc., and further provides the service layer with an open interface to various kinds of network resources in the lower layers. The core transport network of the transport layer is an IP packet network, which provides channels for transmitting various kinds of signaling and media streams. The main functional entity of the access layer is a Media Gateway (MG), which converts other kinds of access formats into Real Time Protocol/Real-time Transport Control Protocol (RTP/RTCP) streams suitable for transmission on the IP network.
Between the MGC and the MG, H.248/MGCP protocol is applied, by which the MGC controls the connection, establishment and release of media streams over the MG.
When connection between the MG and the MGC is broken (i.e., the MG detects that the MGC that is currently controlling it fails), the MG attempts to contact the next MGC in a preconfigured list stored thereon, by following the actions specified in Section 11.5 and appendix F.3.6 of H.248. In practice, on the one hand, many telecommunications operators wish that a call could be held during the course of recovery of the connection between the MG and the MGC. The MG preferably holds the call during the course of connection recovery, so that the MGC is able to check the state of the call after the connection is recovered. On the other hand, some MGC are not able to perform such check after the corresponding connections have been recovered. In this case, the telecommunications operators probably wish not to hold a call during the course of connection recovery. However, the existing H.248 protocol can not satisfy the above requirements.